Pre-Natal Diagnosis of Occult Spinal Dysraphism by Ultrasonography and Post-Natal Evaluation by MR Scanning

Abstract

Eight children born with occult spinal dysraphism were diagnosed in utero by ultrasonography. Post-natally, they were evaluated by MR scans. The ultrasound scans in all 8 fetuses revealed a spina bifida: the spinal cord was long in 5 and in 3 a meningocele was thought to be present, however, in 1, a post-natal MR scan revealed a lipomeningocele instead of a simple meningocele. In 3 fetuses an echogenic area was seen on the ultrasound scan which raised the possibility that an intradural lipoma was present, and was confirmed by post-natal MR scans. In 3 fetuses vertebral body anomalies and an additional ossification centre in a midline bony spur together with widening of the spinal canal were seen in the lower lumbar region. The lesions in all 8 fetuses were skin-covered. None had ventriculomegaly or an Arnold-Chiari malformation. The prognosis for fetuses with spina bifida aperta is well documented in contrast to that for those with spina bifida occulta. The ability to identify a spinal dysraphic lesion pre-natally allows a more accurate assessment to be made of the likely outcome for an individual fetus.

Impact of prenatal magnetic resonance imaging on postnatal neurosurgical treatment

“…[11][12][13][14][15] Small meningoceles or even myelomeningoceles can be mistaken for closed spina bifida with lipomyelocele. The contribution of fetal MR imaging lies in its demonstration of associated brain anomalies such as agenesis of the corpus callosum or migration malformation.…”

Sonographic evaluation of the fetal conus medullaris

“…These anomalies have been mostly reported in the paediatric imaging literature. Data about the prenatal diagnosis of these anomalies are scarce …”

“…Data about the prenatal diagnosis of these anomalies are scarce. 4,5 In addition to the ossification centres and the overlying skin in a transverse, frontal and parasagittal section, the spinal cord and the conus medullaris (CM) can also be visualized as a dark, triangular structure with two surrounding echogenic lines at the caudal end of the spinal cord. With increasing fetal size, the CM is shifted towards the fetal head, from the sacral region to approximately L2 (L: lumbar vertebrae) at birth.…”

Prenatal Evaluation of the Fetal Conus Medullaris on a Routine Scan

“…Defects include tethered cord (tight filum terminale syndrome), diastematomyelia, subcutaneous or interspinal lipoma, and epidermoid and dermoid cysts. These anomalies have been mostly reported in the pediatric imaging literature [5], and the prenatal diagnosis of some of these anomalies has been published [6,7,8]. …”